let age = 25
console.log(age == 25)
console.log(age == 30)
console.log(age != 30)
console.log(age > 20)

let name = "David"
console.log(name == "David")
console.log(name == "Julia")

//严格比较，变量类型也必须相等才返回 ture
console.log(age === "25")
console.log(age !== "25")